EXCEEDTHE SPACE PROVIDED. ~ ~~ ~~ The long-term objective of this proposal is to understandthe perception of multiple abnormalities in an imaging examinationand to developstrategies for improveddiagnostic accuracyand patient outcome.We are one of the few laboratories in the world pursuing the goal of reducing detection errors through a better understandingof the underlying perceptual processesinvolved. Failureto detect an abnormality is the mostcommon classof error in diagnostic imagingand generally is considered the most serious bythe medicalcommunity. Manyof these errors have been attributed to [unreadable]satisfaction of search,[unreadable] which occurswhen a lesion is not reported becausediscovery of another abnormality has [unreadable]satisfied[unreadable] the goal of the search. Although we have gainedsome understandingof the mechanismsof satisfaction of search (SOS),there are significant questions that remain. The failure of human pattern recognition underlying satisfaction of searcherror has not been explained. Our previous researchmay offer the key: the clinical importanceof abnormalities may determinehow much they interfere with detection of other abnormalities. Helicalcomputedtomography(CT) may replace radiographyas the most common and usefulradiologyexamination becauseit offers more accurate and earlier lesion detection. But the large number of images producedby modern CT and other cross-sectional modalities may quickly overload the radiologists' perceptual resources, creating increased risk of satisfaction of search error. There have been no experimental studies of SOS error in the advanced imaging. There arefew interventions that hold promiseto remedySOS error. The goal of computer-aideddiagnosis is to improvecancer detection. Whether computer-aideddiagnosis can reduce SOS error has not been consideredor studied until now. We propose six definitive experimentsto approach the complex questions that remain. The research methodswill include experimentsusing analysis of receiver operating characteristic curves, the time course of detection responses and termination of search, and display commands issued by the observerto interrogate the image data array. The knowledge gainedfrom this programmaticresearch will lead to reduction in observer error.